Alternating-curreet-distributing system



J. C. PARKER.

ALTERNATING CURRENT DISTRIBUTING SYSTEM.

APPLICATION FILED mnze. :91

1,314,895. Piztented Sept. 2,1919.

g 525 @a g 5 INVENTOR Ja/m C/-&r/rer :7 AT'i'ORNEY 1. C. PARKER.

ALTERNATING CURRENT DISIRIBUHNG SYSTEM.

APPLICATION FILED lML29. 19H. PatentedSept. 2,1919.

4 5NEE1'SSHEET 2.

WITNESSES: INVENTOR moa xm- 5 ATTOIRNEY I. 8. PARKER. nmanums CURRENT msmaunm: svsrm.

APPLICATION "LED In. 29. I911. 1,314,895. Patented Sept. 2, 1919. I v 4 SHEETVSHEET 3 wnusszs: INVENTOR $214, )IM John C Fbr/rqr ATTORNEY J. C. PARKER.

ALTEBNATIHG, CURRiNT DISTRIBUflNG SYSTEM.

APPLICATION mm 1.4.29. m1.

1,314,895. 7 Patented Sept. 2, 1919.

4 SHEETS-SHEET 4.

WITNESSES: INVENTOR ya 144.4. :2 BY

, A ITORNEY UNITED STATES PATENT OFFICE.

JOHN C. PARKER, OF ANN ARBOR, MICHIGAN, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ALTERNATIN G- CUBRE III-DISTRIBUTING SYSTEM.

Specification of Letters Patent.

Patented Sept. 2, 1919.

Application filed January 29, 1917. Serial No. 145,226.

To all whom it may concern:

Be it known that I JOHN C. PARKER, a citizen of the United States, and a resident of Ann Arbor, in the county of Washtenaw and State of Michigan, have invented a new and useful Improvement in Alternatin (.lurrent-Distributin Systems, of which t e following is a speci cation.

My invention relates to electrical distributing systems and particularly to distributing net-works for alfernatin currents that are arranged to supply lighting and power service to customers in a city. The present invention provides a net-work comprising the low-tension circuits of an alternatingcurrent distributing system and is patterned, to some extent, after the net-works employed in direct-current distributin systems.

At present, an alternatlng-current distributing system comprises a plurality of independent power-distributing sections. Each of these sections is fed by a transformer having its primary winding connected to the high-tension suppl mains and its secondary winding connecte to the powerdistributing mains forming the independent section. Since the several sections are electrically independent of one another, no benefit can be derived from the time differences in the occurrence of the peak-loads that obtain in adjacent sections. In the event of a short-circuit or a ground being imposed on a section, the fuses of the transformer supplying the section will interrupt the circuit, thus cutting it off from the power supply until the fault is located and the fuses are replaced by an attendant. Heretofore, it has not been desirable to directly interconnect the several sections to one another because the interchange of current between adjacent transformers will, in all robability, when a fault occurs on a section, e suflicient to blow the fuses inserted in the other sections, as a result of the low impedance of the transformers and the low resistance of the interconnecting mains. The trouble, therefore, will be aggravated b the subsequent increase in the area initia ly rendered inactive by the fault.

By means of my present invention, the distributing mains of a net-work are so interconnected to one another, through protective devices, that an interruption of service in any particular section or center of distribution of the net-work is substantially precluded. When a fault or ground occurs on a distributing main of the net-work, the fuses or circuit interrupters that are connected to the primary or secondary windings of the transformer serving the section containing the affected conductor will be actuated, and the adjacent transformers that are connected in the net-work will deliver sufficient current to the affected conductor to clear the fault. At the same time, the protective devices which I employ prevent these transformers from severally sup lying currents of such lar e values to the a ected circuits as to cause t e fuses associated with the transformers to blow.

The same conditions obtain when a transformer becomes grounded. In this case, the adjacent transformers in the net-work deliver, in the aggregate, sufficient current thereto in order to blow the transformer fuses. As a result, the grounded transformer is isolated automatically, and service in the distributing center, previously maintained by the disconnected transformer, will be resumed at a slightly reduced voltage. In other words, service conditions are maintained even though the transformer normally furnishing power to a distributing center is disconnected from circuit. The voltage of the distributing center so fed by the net-work is maintained within a few per cent. of its normal value or that value which was impressed thereon by the disabled transformer.

For a better understanding of the nature and scope of my invention, reference may be had to the following description and the accompanying drawings, in which F gure l is a diagrammatic view of a distributing net-work embodying a form of my invention; Fig. 2 is a, conventional dlagram to more simply illustrate thesystempf Fig. 1; Fig. 3 is a diagram of a distrlbuting system arranged according to my inventlon; Fig. 4 is a simple diagram clearly illustrating the novel features of the system of Fig. 3; Figs. 5 and 6 are diagrams of another orm of my distributing system, and Flg. 7 1s a diagrammatic view showing my invention applied to a three-w1re alternating-current distributing system.

Referring to Fig. 1 high-tension powerdistributing mains 1, t at are connected to a. proper source of power supply (not shown), furnish electric power to big -tens1on feeders 2 and 3. The low-tension distributing net-work comprises a plurality of parallel mains, such as 4 and 5, and a plurality of mains, such as 6 and 7 that, forconvcnien'ce, are shown at right angles thereto. These low-tension distributing mains criss-cross and are interconnected with one another, as shown, to form a plurality of power-distributing centers, such as are indicated at 8, 9, 10 and 11.

The power-distributing center 8 is normally supplied with low-voltage current by means of a transformer 12. The trans' former 12 comprises a primary winding 13 which is connected to the high-tension feeder mains 2 ands low-tension winding 1% that is connected through circuit interrupters or fuses 15 to the low-tension mains 6. Similarly, the distributing centers 9, 10 and 11 are normally supplied with power by means of transformers 16, 17 and 18, respectively.

Since the power distributing centers shown in this fi ure are similar, I will describe the distributing center 8 only. The transformer 12 supplies current to loads 19, 20, 21 and 22 that are connected to the mains 4 and 6 in close proximity to the transformer. Reacts-nee coils 23 are inserted in the mains 6 intermediate the centers 8 and 10, and react-mice coils 24 are inserted in the mains 4- intermediate the centers 8 and 9. Similarly, the other two mains comprising the center 8 are furnished: with reacteince coils 25 and 26. It will be noted, therefore, that the power-distributing center 8 is separated from all the other centers in the network by means of reactance coils inserted in the mains extending to the distributing centers immediately adjacent to the center 8.

It may be assumed that the transformer 12 is so selected that it economically furnishes power to the loads 19, 20, 21 and 22 constituting the center 8. transformers connected to the other centers of the net-work may be so selectedthat'the normal loads severally obtaining therein are economically suppliedwith power means of properly selected transformers. By neasonof this selection, the reactamce coils! 23;

24, 25 and 26 may be inserted at points in the interconnecting mains normally having substantially the same potential difference:

Under normal operating conditions, therefore, the currents traversing the Ieactanee coils, by which the distributing center 8' is bounded, will be very small; The reactance coils are'so proportioned as to limit the currents that may flow lrom each distributingcenter. In consequence thereoflall of the transformers, excepting those connected directly to "distributingoeniers in which fa'u lts develop; are 'liireventecl from becoming even loaded 'tosuch an extent that thein'asso Similarly, the

ciated fuses will blow. While it may be desiruble to s apportion the loads supplied by the transformers of the net-work that each transformer may operate most elliciently, as explained above, this condition is not required of my present system.

Assume that a fault shown, for instance, as it ground develops at 27 in the distributing center 8. The excess current delivered by the transformer 12, which is directly connected to the center 8, will probably blow the fuses 15. At the same time, currents from all of the other distributing centers of the net-work will flow through the protective reactance coils bounding them to the affected center 8. The currents thus supplied to the center 8 will, in the aggregate, be suflicient to burn off and permanently remove the fault developed at 27. While the distributing centers immediately adjacent to the center 8 will furnish currents of higher value than the more remote distributing centers. it is apparent that substantially all of the distributing centers comprising the net-Work will contribute their due share of currents, depending upon their distances from the affected center and their general location in the net-work.

After the fault 27 has been cleared, all of the distributing centers will severally cointinue to furnish their quota of power to the distributing center 8 which, in the aggregate, will be amply suflicient for the loads 19', 20, 21 and 22. Satisfactory service. at a. slightly reduced voltage, is thus automatically resumed after the fault 27 has been removed. The protective reactance devices associated with each distributing center will, of course, prevent any one transformer from supplying an undue portion of the load thus assumed by the remaining transformers connected in the circuit.

-The same conditions obtain when a ground or short circuit develops in the windin s of the transformer 12. In this instance, the currents delivered firom the other distributing centers of the network will, in the aggregalte, blow the fuses 15, thus automatically disconnecting the tlmiisfbrmer winding 14 from circuit. Seri'icein the'distributing centers is, therefore, not interrupted. In any case, the reaetance coils are s'o'designed that the transformer fwes wifl'noti be blown except toremove faults and disabled transformers from the circuit, as explainedin connection with the 'tmnstcrmerlz. At the same timathereactance coils must have slit-- ficiently 10w; impedmcestcprevent abnormally low voltages from being impressed upon a distl'iblltllig center which is devoid of its power-supply means, afterthe conditions causing" trouble therein have been removed.

When a transformer connected to a disti ibuting'. center is called opens-to fumish'am abnormally large amount of power by reason of the local conditions, the other transformers connected in the net-work, which do not happen to be called upon to deliver their rated output at the same time, will assist the overloaded transformer. This tends to raise the load-factor of the entire distributing net-work. As a consequence of this cooperation between the transformers connected in the net-work, smaller units may be installed and the copper losses of the distributing system materially reduced at the peak of the central-station load when the cost of supplying power is most ex ensive. At the same time, the service ren ered the customers is im roved because of the better voltage regulatlon that is maintained in such a net-Work.

The diagram of Fig. 2 is a simplified illustration of a portion of a net-work, similar to the net-work of Fig. 1, in which the mains are represented by single lines only. The relation between the distributing center 8 and the other distributing centers of the not work is more clearly shown. The distributing centers 9 and 10, as well as distributing centers 9 and 10, are directly connected to the distributing center 8 through reactance coils. Distributing centers 11, 1.1, 11 and 11 are connected to the distributing center 8 through parallel paths, each comprising reactance coils. Distributing centers more remote from the distributing center 8 are connected thereto through various paths that traverse the aforementioned distributing centers. It is readily seen that all of the distributing centers of the net-work will contribute power, in some way, to the loads connected in the distributing center 8 when its own power-supply means is reudered inactive.

The portion of Fi 2 inclosed by thc broken line correspon s to the circuit shown in Fig. 1.

The rtion of the distributing net-work shown in Fig. 3 comprises four distributing centers 28, 29, 30 and 31, each of which is formed b four criss-cross mains, whereby at least eight distributing circuits are pro-- vided. As explained in connection with the system shown in Fig. 1, the distributing centers are severally provided with power transformers, each of which, under normal con ditions, has an adequate output for the power requirements of its associated distributing center. The distributing center 28 is connected to the distributing center 31 by means of mains 32 in which reactance coils 33 are inserted. The distributing center 29 is connected to the distributing center 30 by means of mains 34 in which reactance coils 35 are inserted. The distributing center 28 is, therefore, separated from all of the other distributing centers of the net-work by means of reactance coils, such as are shown in Fig. 1. The operation of this system is similar in all respects to the one heleinbefore described.

The portion of the diagram of Fig. 4, included in the area bounded by the broken line 36, corresponds to the portion of the network illustrated in Fig. 3, the latter figure serving to illustrate clearly the relation between the centers 28, 29, 30 and 31 and the other distributing centers comprising the net-work.

Fig. 5' shows a net-work somewhat similar to that of Fig. 3. Each distributing center, however, in this instance, is formed by three cries-cross power mains only, diagonally disposed mains 38 and 39 serving to directly connect distributing centers to one another that otherwise would be connected only through other distributing centers. Fig. 6 is a simplified diagram showing the system of Fig. 5.

In Fig. 7 I have shown a three-wire distributing net-work arranged in accordance with my invention. Power is supplied lo the several distributing centers by means of high-tension mains 40 and high-tension feeder circuits 41, 42 and 43. A distributing center 44 is furnished with power delivered by the high-tension feeder circuit 42 to a transformer 45, having its secondary winding 46 connected to the three-wire low-tension circuit 47. The distributing center 44 is separated from a distributing center 48 by means of reactance coils 49; from a distributing center 50 by means of reactance coils 51; from a distributing center 52 by means of reactance coils 53; from a distributing center 54 by means of rcactance coils 55; from a distributing center 56 by means of reactancc coils 57 and from a distributing center 58 by means of reactancc coils 59. It will be noted that the distributing center 44 is directly connected to the dis-- tributing centers 50 and 56 by means of in terconnecti-ng mains that are shunted to the distributing centers 48 and 58, respectively. The distributing center 44 is thus protected against discontinuity of service by reason of a large number of distributing centers which will serve to deliver an adequate power supply to the loads comprising the distributing center 44 when the transformer 45 is rendered inactive.

In all of the figures, I have shown the mains extending between adjacent distributing centers as being provided with two reactance coils. Of course, under usual conditions, a single coil connected in one conductor of each main will be adequate to properly segregate the several distributing centers from one another. It is obvious, of course, that the character of the reactance devices or current-limiting coils supplied is dependent upon the aggregate loads fed by the several distributing centers, the grouping of the loads, the overload ca vlll') pacity desired of the transformers and other considerations. It is not my intention to describe any particular form of reactance coil to be employed, since current-limiting reactance coils are old in the art and their design and structure depend upon the service to which they are to be subjected.

While I have shown several embodiments of my invention, it will be understood that I desire only such limitations to be imposed thereupon as are limited by the prior art and the appended claims.

I claim as my invention:

1. In a system of distribution, the combination with a plurality of sets of sub-divided mains that are connected to form a plurality of distributing centers having connection with each other through a plurality of paths, of means for supplying power to the several centers, and power-hunting devices connected between the sub-divisions of the mains.

2. In a system of distribution, the combination with a plurality of sets of crisscrossed mains that are connected to each other at their crossings to form a plurality of distributing centers, of means for supplying power to the centers, and power limiting means interposed in the mains between and interconnectin the centers.

3. In a system of distribution, the combination with a plurality of sets of mains each of which is directly and permanently connected to one or more other sets to form a plurality of distributing centers, of means for supplying power to the centers, and power-limiting means interposed in the mains between, and permanently connecting,

the centers wherel'iy each of said centers is maintained substantially independent of all other centers under normal conditions, and whereby, upon the failure of any center to supply the demand upon it, the other centers are enabled to supply the deficit in proportion to their several distances from the defaulted center.

4. A system of distribution comprising a plurality of sets of sub-divided mains, reactance devices interposed between and connecting the sub-divisions, and means for supplying power to the sub-divisions, each set of mains being connected to one or more other sets independently of the connections through the reactance devices.

5. A net-work system of distribution comprising a plurality of sets of subdivided. mains, corresponding subdivisions of two or more sets being respectively interconnected to form a plurality of distributing centers, means for supplying power to the several distributing centers, and power-limiting means interposed between and connecting the subdivisions of each set of mains.

6. A network system of distribution comprising a plurality of sets of subdivided mains, corresponding subdivisions of two or more sets being respectivel interconnected to form a plurality of istributing centers, transformers for supplying power to each of the distributing centers, and reactance devices interposed in the mains be tween the subdivisions thereof.

In testimony whereof, I have hereunto subscribed my name this eighth day of J anuary, 1917.

JOHN G. PARKER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

